Support pt.V (#7)

.github/workflows/test.yaml

@@ -0,0 +1,43 @@
+name: Test
+
+on:
+  push:
+    branches: [ "master" ]
+    tags: [ "v*" ]
+  pull_request:
+    branches: [ "master" ]
+
+jobs:
+
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v3
+
+      - name: Set up Go
+        uses: actions/setup-go@v4
+        with:
+          go-version: '1.18'
+
+      - name: Format
+        run: gofmt -l . && test -z "$(gofmt -l .)"
+
+      - name: Build
+        run: go build -v ./...
+
+      - name: Test
+        run: go test -race -coverprofile=coverage.out -covermode=atomic
+
+      - name: Upload coverage
+        uses: codecov/codecov-action@v3
+        with:
+          token: ${{ secrets.CODECOV_TOKEN }}
+
+      - name: Vet
+        run: go vet -v ./...
+
+      - name: Lint
+        uses: golangci/golangci-lint-action@v3
+        with:
+          version: latest

README.md

@@ -1,7 +1,8 @@
 # pt
 
-[![Build Status](https://travis-ci.com/gochore/pt.svg?branch=master)](https://travis-ci.com/gochore/pt)
-[![codecov](https://codecov.io/gh/gochore/pt/branch/master/graph/badge.svg)](https://codecov.io/gh/gochore/pt)
+[![Go Reference](https://pkg.go.dev/badge/github.com/gochore/pt.svg)](https://pkg.go.dev/github.com/gochore/pt)
+[![Actions](https://github.com/gochore/pt/actions/workflows/test.yaml/badge.svg)](https://github.com/gochore/pt/actions)
+[![Codecov](https://codecov.io/gh/gochore/pt/branch/master/graph/badge.svg)](https://codecov.io/gh/gochore/pt)
 [![Go Report Card](https://goreportcard.com/badge/github.com/gochore/pt)](https://goreportcard.com/report/github.com/gochore/pt)
 [![GitHub go.mod Go version](https://img.shields.io/github/go-mod/go-version/gochore/pt)](https://github.com/gochore/pt/blob/master/go.mod)
 [![GitHub tag (latest by date)](https://img.shields.io/github/v/tag/gochore/pt)](https://github.com/gochore/pt/releases)
@@ -16,181 +17,205 @@ package main
 import "github.com/gochore/pt"
 
 func main() {
-	// wrong
-	f(&100) // can not compile
+	// 💀 It cannot work because Go does not allow taking the address of a constant or literal.
+	f(&100)
 
-	// bad
+	// 😕 It works, but it requires two lines and declares a variable that could pollute the namespace.
 	v := 100
 	f(&v)
 
-	// good
+	// 😊 It works. Only one line and no new variables.
+	// But you have to use different functions for different types.
+	// It's the only way to do it before Go1.18.
 	f(pt.Int(100))
 
-	// good, with generics, need go1.18+
+	// 🤩 It works. Only one line and no new variables, and a single function for all types.
+	// It's based on generics, so it requires Go1.18 and above.
 	f(pt.P(100))
 }
 
-func f(*int) {
+func f(p *int) {
+	// 💀 It could panic if p is nil.
+	println(*p)
 
+	// 😕 It's safe, but it requires multiple lines and declares a variable that could pollute the namespace.
+	v := 0
+	if p != nil {
+		v = *p
+	}
+	println(v)
+
+	// 🤩 It's safe. Only one line and no new variables.
+	// It's based on generics, so it requires Go1.18 and above.
+	println(pt.V(p))
 }
 ```
 
 ## Document
 
-### go1.18 and above
+### Go1.18 and later
 
 #### func P
 
 ```go
-func P[V any](v V) *V
+func P[T any](v T) *T
+```
+P returns pointer of v.
+It's a short form of "Pointer" or "GetPointer".
+
+#### func V
+
+```go
+func V[T any](p *T) T
 ```
-P return pointer of v
+V returns value of p. If p is nil, return zero value of T.
+It's a short form of "Value" or "GetValue".
 
-### before go1.18
+### Before Go1.18 (deprecated)
 
-#### func  Bool
+#### func Bool
 
 ```go
 func Bool(v bool) *bool
 ```
-Bool return pointer of bool
+Bool returns pointer of bool
 
-#### func  Byte
+#### func Byte
 
 ```go
 func Byte(v byte) *byte
 ```
-Byte return pointer of byte
+Byte returns pointer of byte
 
-#### func  Complex128
+#### func Complex128
 
 ```go
 func Complex128(v complex128) *complex128
 ```
-Complex128 return pointer of complex128
+Complex128 returns pointer of complex128
 
-#### func  Complex64
+#### func Complex64
 
 ```go
 func Complex64(v complex64) *complex64
 ```
-Complex64 return pointer of complex64
+Complex64 returns pointer of complex64
 
-#### func  Duration
+#### func Duration
 
 ```go
 func Duration(v time.Duration) *time.Duration
 ```
-Duration return pointer of time.Duration
+Duration returns pointer of time.Duration
 
-#### func  Float32
+#### func Float32
 
 ```go
 func Float32(v float32) *float32
 ```
-Float32 return pointer of float32
+Float32 returns pointer of float32
 
-#### func  Float64
+#### func Float64
 
 ```go
 func Float64(v float64) *float64
 ```
-Float64 return pointer of float64
+Float64 returns pointer of float64
 
-#### func  Int
+#### func Int
 
 ```go
 func Int(v int) *int
 ```
-Int return pointer of int
+Int returns pointer of int
 
-#### func  Int16
+#### func Int16
 
 ```go
 func Int16(v int16) *int16
 ```
-Int16 return pointer of int16
+Int16 returns pointer of int16
 
-#### func  Int32
+#### func Int32
 
 ```go
 func Int32(v int32) *int32
 ```
-Int32 return pointer of int32
+Int32 returns pointer of int32
 
-#### func  Int64
+#### func Int64
 
 ```go
 func Int64(v int64) *int64
 ```
-Int64 return pointer of int64
+Int64 returns pointer of int64
 
-#### func  Int8
+#### func Int8
 
 ```go
 func Int8(v int8) *int8
 ```
-Int8 return pointer of int8
+Int8 returns pointer of int8
 
-#### func  Rune
+#### func Rune
 
 ```go
 func Rune(v rune) *rune
 ```
-Rune return pointer of rune
+Rune returns pointer of rune
 
-#### func  String
+#### func String
 
 ```go
 func String(v string) *string
 ```
-String return pointer of string
+String returns pointer of string
 
-#### func  Time
+#### func Time
 
 ```go
 func Time(v time.Time) *time.Time
 ```
-Time return pointer of time.Time
+Time returns pointer of time.Time
 
-#### func  Uint
+#### func Uint
 
 ```go
 func Uint(v uint) *uint
 ```
-Uint return pointer of uint
+Uint returns pointer of uint
 
-#### func  Uint16
+#### func Uint16
 
 ```go
 func Uint16(v uint16) *uint16
 ```
-Uint16 return pointer of uint16
+Uint16 returns pointer of uint16
 
-#### func  Uint32
+#### func Uint32
 
 ```go
 func Uint32(v uint32) *uint32
 ```
-Uint32 return pointer of uint32
+Uint32 returns pointer of uint32
 
-#### func  Uint64
+#### func Uint64
 
 ```go
 func Uint64(v uint64) *uint64
 ```
-Uint64 return pointer of uint64
+Uint64 returns pointer of uint64
 
-#### func  Uint8
+#### func Uint8
 
 ```go
 func Uint8(v uint8) *uint8
 ```
-Uint8 return pointer of uint8
+Uint8 returns pointer of uint8
 
-#### func  Uintptr
+#### func Uintptr
 
 ```go
 func Uintptr(v uintptr) *uintptr
 ```
-Uintptr return pointer of uintptr
+Uintptr returns pointer of uintptr